/// <summary>
/// Starts a new configuration epoch.
/// </summary>
/// <param name="updateConfiguration">If true, the configuration is also uploaded to the azure storage.</param>
/// <returns></returns>
internal void StartNewEpoch(bool uploadConfiguration)
{
using (CloudBlobLease lease = new CloudBlobLease(GetConfigurationContainer().GetBlockBlobReference(ConstPool.CURRENT_CONFIGURATION_BLOB_NAME), LeaseTakingPolicy.TryUntilSuccessful))
{
if (lease.HasLease)
{
if (uploadConfiguration)
{
UploadConfiguration(lease.getAccessConditionWithLeaseId().LeaseId);
}
try
{
CloudBlobContainer configurationContainer = GetConfigurationContainer();
ICloudBlob blob = configurationContainer.GetBlockBlobReference(ConstPool.CURRENT_CONFIGURATION_BLOB_NAME);
int newEpoch = ++this.Epoch;
blob.Metadata[ConstPool.EPOCH_NUMBER] = "" + newEpoch;
blob.Metadata[ConstPool.EPOCH_MODIFIED_TIME] = DateTimeOffset.Now.ToString();
blob.SetMetadata(lease.getAccessConditionWithLeaseId());
Console.WriteLine("Epoch " + Epoch + " written to the azure and started.");
}
catch (StorageException ex)
{
Console.WriteLine(ex.ToString());
throw ex;
}
}
}
SyncPrimaryServersWithSessionState();
SyncSecondaryServersWithSessionState();
}
/// <summary>
/// By writing an empty string in metadata[EPOCH_NUMBER] of the configuration blob, all clients will eventually read it, and enter the slow mode.
/// </summary>
internal void EndCurrentEpoch()
{
try
{
using (CloudBlobLease lease = new CloudBlobLease(GetConfigurationContainer().GetBlockBlobReference(ConstPool.CURRENT_CONFIGURATION_BLOB_NAME), LeaseTakingPolicy.TryUntilSuccessful))
{
ICloudBlob blob = GetConfigurationContainer().GetBlockBlobReference(ConstPool.CURRENT_CONFIGURATION_BLOB_NAME);
blob.Metadata[ConstPool.EPOCH_NUMBER] = ConstPool.RECONFIGURATION_IN_PROGRESS;
blob.SetMetadata(lease.getAccessConditionWithLeaseId());
}
Thread.Sleep(ConstPool.CACHED_CONFIGURATION_VALIDITY_DURATION);
}
catch (StorageException ex)
{
Console.WriteLine(ex.ToString());
throw ex;
}
}
